1. Field of the Invention
This invention relates to terpolymer hair fixative resins suitable for use in pump and aerosol hair spray compositions, and, more particularly, to an improved method of making such terpolymer resins by solution polymerization of maleic anhydride, vinyl acetate and isobornyl acrylate and to esterified derivatives thereof.
2. Description of the Prior Art
Chuang, in U.S. Patent No. 4,689,379, described a one-step, aqueous suspension polymerization process for the preparation of terpolymers of vinyl acetate, mono-C.sub.4 -C.sub.5 alkyl maleate and isobornyl acrylate in a molar ratio of about 1:0.35-1:0.05-0.25. The reaction mixture comprised particularly vinyl acetate, mono-n-butyl maleate and isobornyl acrylate.
Chuang, in U.S. Pat. No. 4,961,921, described another process for making the terpolymers disclosed in U.S. Pat. No. 4,689,379, having a relative viscosity of 1.10 to 1.30, by polymerizing a mixture of vinyl acetate, mono-n-butyl maleate and isobornyl acrylate as a solution in acetone solvent.
However, these processes are relatively slow requiring 8-20 hours for completion, because the monobutyl maleate reactant did not copolymerize rapidly with the other monomers. In addition, the terpolymer product of the prior art was the mono-alkyl maleate containing terpolymer only.
In view of the limitations of the prior art, it is an object of this invention to provide an improved process for making terpolymers suitable for use in pump and aerosol hair spray compositions, which is characterized by solution polymerization of a monomer mixture comprised of maleic anhydride, vinyl acetate and isobornyl acrylate.
Other features of the invention is the provision of a solution polymerization process in acetone solvent for preparing such terpolymers, which process can be carried to completion in about half the time required of solution polymerization processes employing mono-alkyl maleate as monomer reactant, and which can afford the terpolymer product independently in the form of either the free acid, an ester thereof, or as a hydrolyzed or neutralized derivative thereof.
These and other objects and features of the invention will be made apparent from the following description thereof.